Nowadays big ships have sophisticated equipment to help warn them of any dangers nearby. In the past however, all sea traffic needed lighthouses to warn of rocks or to indicate the entrance to a harbor when visibility was poor. A lighthouse is a tall structure, with a strong, flashing light at the top. In spite of modern technology, such as GPS, lighthouses still have a role to play as a navigational aid [source: Trinity House]. Here's how to build a little model lighthouse.
- Cardboard tube (e.g. empty kitchen roll),
- Bulb holder for 3.5 volt bulb
- 3.5 volt bulb
- One 3 or 4.5 volt battery
- Two wires
- Small plastic jar
- White paper
- Scotch tape
- Two metal paper fasteners
- A small piece of cardboard
Here's what you do:
- Make three or four thin black stripes on the white paper, so that it's now black-and-white striped paper.
- Glue the paper to the cardboard tube so the stripes are horizontal.
- Secure the bulb holder to the top of the tube with scotch tape.
- Attach two of the wires to the connectors on the bulb holder, and run them through the inside of the tube.
- Connect one free end of wire to one terminal of the battery.
- Attach the other free end of wire to one of the paper fasteners. Attach the paper fastener to the battery terminal.
- Attach the other paper fastener to a piece of cardboard, so you don't have to hold it directly when you make the fasteners touch.
- Cut a hole in the cardboard tube, to access the wires.
- Stand the cardboard tube on a piece of cardboard. Tape it into position with Scotch tape, to ensure that it remains up straight.
- Put the bulb in the bulb holder.
- Place the small jar over the bulb.
- When you touch the two paper fasteners to each other, the electric current will flow and the light will go on. You can make it flash by repeatedly touching together and moving apart the fasteners [source: Togher School].